Provided by: radiance_4R1+20120125-1.1_amd64 
NAME
pvalue - convert RADIANCE picture to/from alternate formats
SYNOPSIS
pvalue [ options ] [ file ]
pvalue -r [ options ] [ file1 [ file2 file3 ] ]
DESCRIPTION
Pvalue converts the pixels of a RADIANCE picture to or from another format. In the default mode, pixels
are sent to the standard output, one per line, in the following ascii format:
xpos ypos red green blue
If no file is given, the standard input is read.
The reverse conversion option (-r) may be used with a single input file or when reading from the standard
input, but if the second form is used with three separate input files, the three primaries are presumed
to be separated in these files.
-u Print only unique values in the output, skipping runs of equal pixels. Specifying +u turns
this option off, which is the default.
-o Print original values, before exposure compensation. If the input file is in XYZE format, the
Y (green) channel will correspond to units of candelas/meter^2. Otherwise, the RGB values
should be in spectral watts/steradian/meter^2. Specifying +o uses final exposed values, which
is the default.
-h Do not print header. Specifying +h causes the header to be printed, which is the default.
-H Do not print the resolution string. (See also the -r option below.) Specifying an input
resolution for reverse conversion also turns this option off. Specifying +H causes the
resolution string to be printed, which is the default.
-s nbytes Skip the specified number of bytes on the input header. This option is useful for skipping
unintelligible headers in foreign file formats. (Does not work when reading from standard
input.)
-e exposure
Adjust the exposure by the amount specified. If the exposure is being given as a conversion
factor, use +e instead, so an EXPOSURE line will not be recorded in the header (if any).
-g gamma Set gamma correction for conversion. When converting from a RADIANCE picture to another
format, the inverse gamma is applied to correct for monitor response. When converting to a
RADIANCE picture (-r option), the gamma is applied directly to recover the linear values. By
default, gamma is set to 1.0, meaning no gamma correction is performed.
-d Data only, do not print x and y pixel position.
-da Same as -d.
-di Print ascii integer values from 0 to 255+. If +di is given, the integer values will be
preceded by the x and y pixel locations.
-db Output binary byte values from 0 to 255.
-dw Output binary 16-bit words from 0 to 65535.
-dW Output binary 16-bit words from 0 to 65535, byte-swapped.
-df Output binary float values.
-dF Output byte-swapped binary float values.
-dd Output binary double values.
-dD Output byte-swapped binary double values.
-R Reverse ordering of colors so that the output is blue then green then red. The default
ordering (specified with +R) is red then green then blue.
-n The RGB values are non-interleaved, meaning that all the red, green and blue data are stored
together in separate chunks. Interleaving may be turned on with the +n option, which is the
default.
-b Print brightness values rather than RGB. Specifying +b turns this option off, which is the
default.
-pP Put out only the primary P, where P is one of upper or lower case 'R', 'G' or 'B' for red,
green or blue, respectively. This option may be used to separate the Radiance primaries into
three files with three separate runs of pvalue, or only one file when only one primary is
needed. Note that there is no space between this option and its argument.
-r Perform reverse conversion. Input is in the format given by the other options. The x and y
resolution must be specified on the command line, unless the image file contains a Radiance
resolution string at the beginning (see -H option above and -y option below). Specifying +r
converts from a Radiance picture to other values, which is the default.
-p xr yr xg yg xb yb xw yw
On reverse conversion, RGB input uses the given set of color primaries. These are written into
the output header with the PRIMARIES variable.
-pXYZ On reverse conversion, input is in CIE XYZ coordinates, rather than RGB. The Y channel is
assumed to be in candelas/meter^2.
-y res Set the output y resolution to res. If +y is specified, then the scanlines are assumed to be
in increasing order (ie. bottom to top). The default value for this option is 0, which means
that the picture size and scanline order must appear as the first line after the header (if
any) in the input file. Either an upper or lower case 'Y' may be used for this option. Since
Radiance files always contain such a line, this option has no effect for forward conversions.
+x res Set the output x resolution to res. If -x is specified, then the scanlines are assumed to be
in decreasing order (ie. right to left). The ordering of the -y and +x options determines
whether the scanlines are sorted along x or along y. Most Radiance pictures are sorted top to
bottom, then left to right. This corresponds to a specification of the form "-y yres +x xres".
Either an upper or lower case 'X' may be used for this option. Like the -y option, -x options
have no effect for forward conversions.
EXAMPLE
To look at the original, unique pixels in picture:
pvalue -o -u picture | more
To convert from a 512x400 8-bit greyscale image in bottom to top, left to right scanline ordering:
pvalue -r -db -b -h +y 400 +x 512 input.im > flipped.hdr
pflip -v flipped.hdr > final.hdr
AUTHOR
Greg Ward
BUGS
The -r option does not work with the -u option. Also, input pixel locations are ignored during a reverse
conversion, so this information is not used in determining the scanline ordering or picture size.
SEE ALSO
getinfo(1), pcompos(1), pfilt(1), pflip(1), protate(1), ra_xyze(1), rpict(1), rtrace(1), rvu(1)